Calculating machine with instruction modifying mechanism



A. M. PASINSKI ETAL 3,042,294

July 3, 1962 CALCULATING MACHINE WITH INSTRUCTION MODIFYING MECHANISM Filed Oct. 20, 1958 7 Sheets-Shet 1 PAS/N570. S/EGEL TIII/ INVENTORS Al? 7741/)? M. 474;? T/ N W14 FM A TTOR/VEY.

July 3, 1962 A. M.VPASINSKI ETAL 3,042,294

CALCULATING MACHINE WITH INSTRUCTION MODIFYING MECHANISM Filed Oct. 20, 1958 7 Sheets-Sheet 2 E Q Q N p \o m R a 2 A T TORNE).

July 3, 1962 A. M. FIASINSKI ETAL 3,042,294

CALCULATING MACHINE WITH INSTRUCTION MODIFYING MECHANISM Filed Oct. 20, 1958 7 Sheets-Shet s l 200 ZOZ NVENTORS- ARTHUR PAS/NS/f/ /yA/ET/N .S/EGEL A TTORNE Y.

July 3, 1962 CALCULATINGMACHINE WITH INSTRUCTION MODIFYING MECHANISM Filed Oct. 20, 1958 Fig.5.

A. M. PASlNSKl ETAL 7 Sheets-Sheet 4 I INVENTORS B/y/H? 7'//V S/EG-EL.

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CALCULATING MACHINE WITH INSTRUCTION MODIFYING MECHANISM Filed Oct. 20, 1958 7 Sheets-Sheet 5 INVENTORS M. PAS/A/SKL gAPT/N SIEGEL.

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July 3, 1962 A. M. PASINSKI ETAL CALCULATING MACHINE WITH INSTRUCTION MODIFYING MECHANISM Filed Oct. 20, 1958 7 Sheets-Sheet 6 INVENTORS. ARTHUR M- PAS/A/SKZ B YWART/N \S/EG-EL, m W

AT TORNEY- July 3,1962 A. M. PASINSKI ETAL 3, 42, 4

CALCULATING MACHINE WITH INSTRUCTION MODIFYING MECHANISM Filed Oct. 20, 1958 7 Sheets-Sheet '7 INVENTORS ARTHUR M. PAS/NSKL gA/QT/N 6/EGEL.

A TTOPNEY.

United States Patent Ofifice 3,042,294 Patented July 3, 1962 3,042,294 CALCULATING MACHINE WITH INSTRUCTIQN MODIFYING MECHANISM Arthur M. Pasinski, Detroit, and Martin Siege], Oak Park,

Mich., assignors to Burroughs Corporation, Detroit,

Mich, a corporation of Michigan Filed Oct. 20, 1958, Ser. No. 763,260 2 Claims. (Cl. 235-6047) This invention relates generally to calculating machines and particularly to a mechanism for actuating the arithmetical function control of an amount accumulator of such machines.

It is an object of our invention to provide for an accumulator arithmetic-a1 function control, an improved actuating mechanism to eifect from a function instruction either the predetermined arithmetical function called for thereby or a different function than that called for by the instruction, as desired.

Another object of the invention is to provide, in association with the program sensing lever of a calculating machine, lever operation modifying devices operable at the will of the machine operator to effect the opposite of the arithmetical function called for by the program.

Another object of the invention is to provide an improved mechanism of the above mentioned character for correcting operatorqmade entry errors under carriage con-trol such that the correction will be made automatically in each and every column of a ledger sheet where the error appears.

Another object of the invention is to provide an improved mechanism of the above mentioned character having a novel co-active mechanism to insure the proper resetting of the reverse entry mechanism.

A further object of the invention resides in the provision of automatic error correction under carriage control in the several columns of a ledger card, initiated by depression of both a reverse entry key and a motor bar by the machine operator together with automatic return of the mechanism to normal operation upon completion of the error correction operations.

Other objects of the invention will become apparent from the following detailed description, taken in con nection with the accompanying drawings in which:

FIG. 1 is a side view partly broken away of a calculating machine embodying features of the invention;

FIG. 2 is a view similar to FIG. 1 showing certain of the operating parts of the machine;

FIG. 3 is a side view of a keyboard fragment and interconnecting mechanism that connects a key to a certain control of our instruction modifier operating mechanism;

FIG. 4 is an enlarged side view of the instruction modifier operating mechanism;

FIG. 5 is a plan view of the mechanism of FIG. 4;

FIG. 6 is an elevational view taken along line 6-6 of FIG. 5;

FIG. 7 is a detail perspective view;

FIGS. 8 and 8A are fragments of a side view similar to :FIG. 3, showing the parts in the positions they will assume to efiect cycling operation of the machine;

FIG. 9 is a fragmentary rear view of certain mechanism of the machine shown removed therefrom;

FIG. 10 is a rear view similar to FIG. 9 showing the parts of the mechanism in other positions they will assume;

FIG. 11 is a fragmentary view of the mechanism of FIG. 10 illustrating operation of the mechanism;

FIG. 12 is a perspective view of the mechanism of FIGS. 9 and 10; and

FIG. 13 is another perspective view of the mechanism of FIGS. 9 and 10.

In the drawings there is shown in part a business or accounting machine which is shown and described in detail in the patent to Thomas M. Butler No. 2,629,549 to which reference may be made for a complete understanding of all of the various mechanisms of the machine. In the present disclosure, there is shown only the structure and mechanisms that are directly related to the invention, the structure including the usual supporting frame 20 of the machine having laterally spaced upright side plates 22. Mounted on the front of the frame 20 between the side plates 22 is a keyboard unit 24, and on the rear a carriage 26 which carries a roller type platen 28 and a static program unit 30. A print mechanism is mounted as usual adjacent to and forwardly of the platen 28 and may be of any suitable type, such as the vertically movable print head 32 and print hammer 34. Below the key-board 24 is a pair of accumulators or crossfooters 36 and 38 of a well known type that are adapted to accumulate, in the algebraic sense, amounts indexed additively or subtractively into the machine. The crossfooters 36 and 38 operate, with respect to the arithmetical function per-formed thereby, in accordance with instructions from the program unit 30 which is operatively connectcd to the crossfooters by interconnecting mechanism hereinafter described.

The keyboard 24 includes the usual keyboard frame 40 on which are mounted a plurality of rows of amount keys 4-2 of which only one row is shown (see FIG. 1).

Also mounted on the keyboard 24 (see FIG. 2) are a number of machine function control keys which may include among others, a sub-total key 44, a non-add key 46, a subtract key 48 and a motor bar or machine cycling key 50. In addition, a key 52 is provided which is termed a reverse entry key, since depression of this key will effect theindexing into the machine in reverse order in an algebraic sense, of an amount previously entered.

A main cam shaft 54 is shown having a number of cams 56 which in relative timed relation operate substantially all of the several mechanisms of the machine when the motor bar is depressed. This includes the operation of differential stop slides 57 which control movement of a like number of differential amount racks 58. As is well known in such machines, when the motor bar 50 is depressed, a cycle of operation of the machine is initiated which includes movement by the main shaft cams 56 of all of the racks 58 forwardly against limits established by the stop slides 57 and then rearwardly to their startingpositions. In the present machine, the rearward movement of the amount racks 58 is employed to enter amounts additively into the accumulators and the forward movement of the amount racks is employed to enter the amounts subtractively. To accomplish this, a pair of parallel slides 60 and 62, operated from the main cam shaft 54 are provided, the slide 60 being an add slide and slide 62 a subtract slide, and each of the accumulators 3'6, 38 has a function control means, or selector lever 63 and 64, respectively which are operable to connect one or the other of the slides 60, 62 operatively to levers 65. As is well known, the timing of the cams 56' is such that the subtract slide 62 is moved rearwardly following which the amount racks 58 move forwardly, and the add slide 60 moves rearward'ly after the amount racks move forwardly. The selector levers 63-and 64 are bail or hell crank levers, each having a pair of offset arms 66 and 68 and each arm having a hooked end adapted to engage a stud 70 carried by each of the add and subtract slides 60 and 62. Normally, the selector levers '63, 64 are connected to the add slide 60 such that add operation is the normal operation of the machine. Springs 72 bias the selector levers 63, 64 to engage the studs 70 of the add slide 60. The selector levers 63, 64 are mounted on and pivot levers 65 which move a cam (not shown) to swing the pinions 67 upwardly about pivot 69 to engage the amount racks. The selector levers 63, 64 may be pivoted to engage the subtract slide 62 by depressing the subtract key 48 which is operatively connected to the selector levers by means of interconnecting linkage including levers 74, 76 and 78. Also as Will be hereinafter seen, the selector levers 63, 64 are moved to engage the subtract slide 62 under control of the program unit 30.

The program unit 30 is a well known device which comprises basically a plate 80 and a plurality of instruction members or pins 81, 82. The plate 88 is secured to the underside of the carriage 26, and the pins 81, 82 are attached to and depend from the underside of plate 80. For add operation in the present machine, no pin is required in the program for the reason that the selector levers 63, 64 as previously described are normally connecting the add slides 60 to the crossfooters 36 and 38. Pin 81 is the subtract pin and pin 82, the non add in, and as is well known, the length of these pins determines the instruction called for thereby. While the present invention is concerned only with the functions of calculating machine accumulators, it will be understood by those skilled in the art that the program unit 30 contains stop dogs (not shown) which effect columnar tabulation of the carriage to the end of accomplishing controlled movement of the carriage to positions required for the printing of an amount in several different columns of a ledger card.

Operatively connecting the pins 81, 82 and the accumulator control levers 63, 64 is a pair of motion transmitting members or levers 84 and 86, respectively. These levers 84 and 86 sense the presence of the pins 81 and 82 by means of a pair of vertically movable tappets 88 and 89 to which free ends of the levers 84 and 86 are respectively and pivotally connected, as at 90. The tappets 88 and 89 are mounted on and guided in their vertical movement by support 92. It will be apparent that when no pin is above the tappets 88 or 89, the tappets will be allowed to move upward the maximum distance tothe positions shown, limited by the upper flange of support 92, and that the presence of the non-add pin 82 or of the subtract pin 81 will limit movement of the tappets to corresponding and relatively different positions.

A cam shaft 94 having a pair of cams 96 and 98 thereon is driven from main cam shaft 54 by interconnecting means including gears 97 and 99 (not shown) such that the shaft 94 is rotated each cycling of the machine to pivot the levers 84, 86 about the fulcrums 90. Each of the levers 84, 86 has, intermediate its ends, a downwardly directed follower arm 100 carrying a roller 102 to engage the periphery of the respective one of the earns 96 and 98, the follower rollers 102 each being held in contact with the cam surface by a spring 104.

The levers 84 and 86 are each operatively and individually connected to the function selector levers 63, 64 of the accumulators 36, 38 by interconnecting mechanisms each of which includes abell crank lever 106', link 108, levers 110, link 112, lever 114, link 76 and lever 78. Thus, for example, when the subtract pin 81 is sensed by lever 84, the corresponding movementof the lever allowed by said pin is transmitted by lever 84 via the interconnecting mechanism including lever 78 to pivot lever 63, 64 clockwise to disengage the add arm 66 from the add slide 60 and engage the subtract arm 68- with the subtract slide 62. When the non-add pin 82 is sensed, the selector lever affected is moved to neutral position or a position in which it is not engaged with either the add slide 60 or the subtract slide 62.

Carried by each of the sensing levers 84 and 86 is a function modifier or slide 116 and 117, respectively, which have retracted or normal positions as shown in FIG. 9 and extended positions as shown in FIG. 10. In either position, the slides 116, 117 extend beyond the free ends of the levers 84 and 86 and on the outer end of each slide, there is provided a relatively 'low abutment surface 118, a clearance opening 120, a second relatively low abutment surface 122, substantially at the same level as abutment surface 118, and a relatively high abutment surface 124. The abutment surfaces 118, opening 128 and abutment surfaces 122 and 124 are respec tively referred to as normal, reverse of subtract, nonadd, and reverse of add positions of the slide 116.

The slides 116, 117 extend longitudinally of the sensing levers 84 and 86, the slides being slidably supported on the levers on pins 126 in slots 128, the pins being secured to and extending laterally from the levers. Extending substantially coextensive of the levers 84 and 86, the slides 116, 117 have corresponding downturned ends 132 providing an abutment on each which is adapted to engage horizontally spaced stops 134 and 136 which correspond respectively to clearance opening and abutment 122 on the other ends of the slides. One end, designated 131 of slot 138 provides a stop which corresponds to the abutment surface 124, as illustrated in FIG. l0 to align abutment 124 with the under edge of lever 106. The stops 134 and 136 are provided on the edges of upturned flanges of a bracket 142, secured to the tappet support 92. A tension spring 144 for each of the sensing levers 84 and 86 acts to move the slides 116, 117 to the extended positions thereof, limited by one of the stops 131, 134 and 136, depending upon the instruction sensed.

Since the levers 84 and 86 are alike in structure and operation, the following general description of the normal operation has reference only to lever 84 so as to avoid unnecessary repetitious description. In normal position (see FIG. 9) when the lever 84 senses the absence of a function control pin in the program unit 30, the lever pivots counterclockwise on cam 96 to the upper limit of tappelt 88. The upper limit of the tappet 88 is located such that the right end of lever 84 will swing upwardly a distance equal to the rise of cam 96 so that when the cam 96 rotates, the lever 84 will be returned thereby to its normal position. This means, of course, that no motion is transmitted to the accumulator selector lever 63 and as a consequence hook 66 remains connected to slide 68 and the normal add operation is performed. When a subtract pin 81 is sensed by lever 84, the right end of the lever swings upwardly, limited by pin 81, a distance less than the rise of cam 96 with the result that when lever 84 is pivoted by the cam 96 about fulcrum 90, the lever pivots beyond its normal position sufiiciently to move the accumulator function selector 63 to disengage it from the add slide 60 and engage it with the subtract slide 62. Similarly, when sensing a non-add pin, the limit of movement of the lever 84 is such that the accumulator function selector is moved to neutral position, or disengaged from both of the slides 68 and 62.

With the exception of the instruction modifier slides 116, and 118, the above mechanisms are old in the art, as shown by the above mentioned patent to Thomas M. Butler.

In accordance with our invention, the sensing levers 84 and 86 have normal starting positions shown in FIG. 9 for normal operations and have second starting positions, one of which is shown in FIG. 10, for reverse entry operations. Establishing the normal starting positions of levers 84 and 86 is a limiting member or slidable plate which is retractable for releasing the levers to permit them to move mother or reverse entry starting positions. The levers 84 and 86 are guided by the usual comb guide 152 and welded or otherwise secured to the comb guide 152 is a mounting plate 154 for the limit plate 150. The limit plate 150 is vertically disposed and has horizontally elongated slots 156 to receive studs 158 that are secured to the mounting plate 154 for slidably guiding the limit plate 150. The lever-s 84 and 86 extend transversely to the limit plate, and normally rest on the upper edge thereof which upper edge establishes the normal star-ting positions of the levers. In the upper edge of the limit plate 150, adjacent the levers 84 and 86 is a cutout 160 which allows lever 86 to pivot counterclockwise on cam 96 to a second or reverse entry starting position, such as the position shown in FIG. 10, when the limit plate 150 is retracted from the normal position thereof. Also, when the limit plate 150 is retracted, lever 84 slips off the edge of the plate and pivots to its second starting position. It is to be understood that the lower edge 160 of the slide plate 150 is not a limit for lever 84 for, as will later be seen, the angular distance through which the lever will pivot is determined by the instruction pin sensed by the lever. For reverse entry operations, second or reverse entry starting positions of levers 84 and 86 are established by retraction of limit plate 150, the levers being urged to the new positions by the springs 104. Connected to a lug 164 on limit plate 158 is one end of a tension pring 166 which has its other end anchored to a bracket 168 that is mounted on the com 152. The spring 166 acts to return the limit plate 150 to its normal position.

In accordance with the invention, there is provided and slidably supported on the mounting plate 154 a control or slide 170 (see FIGS. 3 and 8A) which is operatively connected to the reverse entry key 52 by interconnecting mechanism including a link 172, levers 174, 176 and slide 178. A coil spring 179 acting on link 172 acts to move slide 170 and the interconnecting mechanism to their normal positions.

When the reverse entry key 52 is depressed, slide 178 is moved rearwardly thereby and pivots lever 176 in a clockwise direction, as viewed in FIG. 3, which allows a spring 180 to engage a link 182 with the lever 174. This sets up the operation for moving slide 150 to its retracted or reverse entry position preparatory to depression of the motor b ar50. Link 182 is pivotally connected to the upper end of one arm 184 of [a bail which has a second arm 186 connected by a stud 188 to a lever 190. A helical coil spring 192 anchored to the machine frame and connected to stud 188 is acting to move link 182 rearwardly to retract the slide 1'70. However, the spring 192 is normally restrained by a lever 194 (see FIG. 8) which normally abuts the lower end of lever 191. Lever 194 is operatively connected by another lever 196 to the stem, as at 198, of the motor bar 50, the arrangement being such that depression of the motor bar pivots lever 194 which releases spring 192 to pull the slide 170. Depression of motor bar 58 also initiates, by mechanism not shown, a cycle of openation of the machine following operation of the slide 170.

In the slide 170 are horizontally spaced slots 200 which receive studs .282 that are secured to the mounting plate 154 for slidably supporting the slide 170. The slide 170 is connected to the limit plate 150 by a latch member 204 which is pivoted by a pin 206 to slide 170 and has a hooked end 208 adapted to engage a lug 210 on limit plate 150 to couple the plates for movement together to the left (FIGS. 3 and 4), when the reverse entry key 52 and the motor bar 50 are both depressed. The latch member 204 is provided so that limit plate 150 can be released from slide 170 for return of plate 150 to normal position by spring 166 before the levers 84 and 86 swing down below their normal positions. This insures that the limit plate 150 will return in ample time beneath the levers 84 and 86, irrespective of whether or not the machine operator releases the reverse entry key 52.

In addition to controlling the starting positions of levers 8'4, 86, the slide 170 also controls the shifting of the function modifier slides 116, 117, between normal and extended or reverse entry positions. To accomplish this, a holder or latch type lever 212 is provided for each of the modifier slides which lever has a lower foot 214 seating on a keeper or lug 216 on the slide 170 in such manner as to act as a stop against rotation of the lever counterclockwise (see FIG. 9) when the limit plate 150- is in normal position. In the latched position of the lever 212, the free or upper end thereof engages a lug 218 carried by the function modifier slide 116 and holds the slide retracted or in normal position against the counteraction of spring 144, thus restraining spring 144 while the limit plate 150 is in normal position. When the limit plate 150 is shifted to reverse entry position, the lever 212 pivots counterclockwise which releases spring 144 to shift the function modifier slide 116, or 117, as the case may be, to the extended or reverse entry positionshown in FIG. 10. Lever 212 is fixed on a shaft 220 that is journaled to rotate on the mounting plate 154, and secured to lever 212 is an arm 222 which is engaged by a lug 224 on cam 96 to relatch the lever foot 214 with the lug 216 of slide 170 and return lever 212 to the normal position thereof. Pivoted on shaft 220 is a latch actuator or lever 226 which has a striker surface 228 in the path of a lug 230 that is carried by cam 98, the lever 226 further having a foot 232 under and adjacent a lug 234 on the latch member .204. Thus, when the cam lug 230 strikes and pivots actuator lever 226, the lever in turn pivots and disengages the latch member 204 to allow the limit plate 150 to return to normal position. A tension spring 236 acts to urge the latch member 204 into coupling engagement with the lug 210, and a coil spring 238 acts to return lever 226 to its normal position shown in FIG. 9. From the above, it will be seen that the limit plate 150 functions to change the starting position of the sensing levers 84 and 86 from the normal starting positions to the second or reverse entry starting position and also through levers 212 control extension and retraction of the function modifier slides 116, 117.

Normal Operation During normal operation, the machine operator enters an amount by means of amount keys 42 and then depresses the motor bar 50 which initiates a cycle of operation of the machine in the well known manner. Assuming that the carriage controlled program 30 has the instruction pins 81 and 82 atrranged to effect an add operation, a subtract operation and a non-add operation, the amount entered in the machine will be added in the accumulator 36, subtracted in the accumulator 38, and/ or non-added, and the amount is also printed across the ledger card and might be printed in the third column although not added in either accumulator. With respect to the operation of the accumulator function control levers 63, 64, the add operation, as previously mentioned will not affect the levers since they are normally in add positions. When the carriage 26 moves to the next columnar position, the program subtract pin 81 will be in position to be sensed by the lever 84 when the lever is pivoted by cam 96 following depressing of motor bar 50. The lever 84 will be pivoted on the top edge of slide 150 as a fulcrum until the tappet 88 engages pin 81 after which the lever will pivot clockwise about the fulcrum 90 on the tappet. The clockwise pivotal movement of lever 84 pivots bell crank 106 and through the interconnecting levers and links will move the function selector 63 out of engagement with add slide 60 and into engagement with subtract slide 62. As a consequence, the accumulator pinion 67 is meshed with the amount racks on return of the latter to home position which enters the amount into the accumulator subtractively. The carriage now moves to the next columnar position where the non-add pin 82 is sensed by the sensing lever 86 and the machine is now cycled by the carriage program control and cam 98 pivots lever 86 first in a counterclockwise direction on slide to sense pin 82 and then in a clockwise direction about fulcrum 90. This movement is transmitted by bell crank. 106 and the associated levers and links to the function selector lever 64 which will be moved to the intermediate or neutral position, disconnected from both the add slide 60 and the subtract slide 62. Consequently the amount entered by the machine operator will not be entered in. the accumulator 38.

Revers'e Entry Operation In the event the machine operator makes an error on the keyboard and the wrong amount is entered in the ac-- cumulators 36, 38, correction can be automatically obtained by re-entering the erroneous amount on the keyboard and cycling the machine with the re-entry key 52. depressed. Depression of the reverse entry key 52 conditions the mechanism (see FIG. 3) by pivoting lever 176 clockwise to allow lever 182 to engage the upper end of lever 174 which connects the slide 170 with the motor bar controlled lever v190. The limit member 150 being; coupled to slide 170 by latch 210 will move with slide: 170 which allows the sensing levers 116 and 118 to pivot under the actions of springs 104- until the levers reach their second or reverse entry starting positions.

The reverse entry starting positions to which the levers 84 and 86 pivot with respect to the rise of earns 96 is. such that in the add position of the carriage, i.e., the no pin position, the movement of lever 84 now is sufficient tomove the function selector lever 63 to subtract position. At the same time that the limit plate 150 is moving toitsreverse entry position, the cams 96 and 98 are rotating and when the lug 230 on cam 98 strikes and pivots lever 226, the latch 204 is disengaged by lever 226 and limit plate 150 immediately returns to the normal position thereof, clearing lever 84 which by this time has been pivoted by the cam 98 upward out of the way of plate 150, Also, movement of the limit member 150 is to its reverseentry position disengages the said member from lever 212 which releases spring 144 and allows the spring to shift the function modifier lever 116 to the position limited by the stop 131, as shown in FIG. 10. In this position, the abutment surface 124 termed the reverse of add is beneath the end of the bell crank 106, the lever 84 acting through the bell crank and associated interconnecting mechanism moves the function selector lever 63 to subtract position. Thus, although the sensing lever 84 was sensing the add instruction, the lever 84 functioned to effect a subtract operation at the accumulator 36. As previously mentioned, the limit member 150 is unlatched from slide 170 soon after cam 96 starts to raise lever 84- so as to insure that the limit member will be in normal position under the sensing levers 84, 86 when they return following operation of the function control lever 63. Finally, the abutment 224 on cam 96 strikes arm 222 of lever 212 which pivots clockwise and through abutment 218, shifts slide 116 to the right (see FIG. 9), which allows spring 179 to restore slide 170 and latch lever 212 at 214 to the slide 170. At the same time, latch 204 is moved into latching engagement with lug 210, thus restoring the parts of the mechanism to the positions shown in FIG. 9. The carriage 26 then moves to the next columnar position and the reverse entry operation is repeated except this time the instruction modifier slide 116 is shifted by the spring 144 to position 120, referred to as the opposite of subtract the slide being stopped by abutment with stop 134. In the next columnar position of the carriage 26, the instruction modifier slide 116 is shifted to the non-add position 122 and the operation repeated. Thus by merely depressing the reverse entry key 52 and the motor bar 50, the machine will operate automatically under carriage control to reverse an erroneous amount entered in the several accumulators and printed in the corresponding columns of the ledger card. This eliminates the need of the operator to make the correction in each column.

While I have shown and described by invention in considerable detail, it will be apparent to those skilled in the art that many changes and variations may be made without departing from the spirit and scope of the invention.

What is claimed is:

1. In a calculating machine, an instruction representing element, a lever operable to sense said element, said lever having a normal starting position and a second starting position, a cam operable to pivot said lever from either of said starting positions, a spring acting to pivot said lever on said cam to said second starting position, a 'shiftable extension member carried by and movable along said lever, said extension member having a normal position representative of the instruction function and a second position representative of a function opposite of the function represented by said element, a spring acting to shift said shiftable member to the second position thereof, a second lever normally engaging and holding said extension member in the normal position thereof, a key operated slide, a stop member carried by said slide and normally holding said first lever in the normal position thereof and retractable to release said first lever, a latch member carried by said slide and normally latching said stop member to said slide, normally engaged latch means on said slide and on said second lever releasable by and upon retraction of said stop member by said slide, a latch actuator operable to release said latch member, and means on said cam to activate said latch actuator.

'2. In a calculating machine, an accumulator control means operable to effect the functions of either a positive or a negative accumulation of amounts, a sensing lever having a normal starting position; a sensing pin representative of one of the functions, a cam operable to move said lever into sensing relationship with said pin and then pivot said lever in one direction, an abutment member operatively connected to said control means, said abutment member mounted on and movable relative to said lever between a normal position and a second position,

said abutment member in normal position being representative of the other of said functions, a spring acting to pivot said lever to a second starting position, a retractable stop member normally engaging and stopping said lever in the normal starting position thereof, a spring acting to shift said abutment member to the second position thereof, said stop member retractable to release said lever to pivot to a second starting position, a spring acting to move said stop member to the normal position thereof, a key operated movable member, a latch member normal- 1y connecting said movable member to said stop member for moving the latter to its second position, said stop member in its normal position releasably restraining said second named spring, means carried by said cam and, operable to release said latch member to effect return of said stop member to normal position, and means carried by said cam operable to return said abutment member to normal position.

References Cited in the file of this patent UNITED STATES PATENTS 2,298,202 Crosman Oct. 6, 1942 2,626,749 Christian et a1. Jan. 27, 1953 2,692,726 Frieberg et al. Oct. 26, 1954 

